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RESEARCH PRODUCT

Reactivity of the di-μ-hydroxo-complexes [{Pd(NN)}2(μ-OH)2][ClO4]2 (NN=bis(pyrazol-1-yl)alkanes) towards protic electrophiles. Hydration of coordinated nitriles at a palladium(II) site

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Abstract The hydroxo-complexes [{Pd(μ-OH)(NN)}2][ClO4]2 (NN=bpzm:bis(pyrazol-1-yl) methane: a-compounds, bpzm*:bis(3,5-dimethylpyrazol-1-yl)methane; b-compounds) react with a wide variety of weak protic electrophiles H(LL) in a 1:2 molar ratio to give the mononuclear cationic palladium(II) derivatives of general formula [Pd(LL)(NN)][ClO4] [LL=2-pyridine-methoxo (OCH2-py) (1a,b); picolinate (pic) (2a,b); 8-hydroxiquinolinate (oxin) (3a,b)] or the dinuclear complexes [{Pd(NN)}2(μ-ox)][ClO4]2 [ox=oxalate: (4a,b)] and [{Pd(μ-LL)(NN)}2][ClO4]2 [LL=pyrazolate (pz) (5a,b); p-thiocresolate (SC6H4Me-p) (6a,b); triazolate (tz) (7b); thiophenolate (SPh) (8b)] when reacting with oxalic acid, azoles or thiols in the same molar ratio. In a related reaction, deprotonation of secondary amines by the hydroxo-complexes in the presence of carbon disulfide leads to the corresponding dithiocarbamate complexes [Pd(S2CNR2)(NN)][ClO4] [R=Me (9a,b), Et (10a,b) C5H10 (11a,b)]. The hydroxo complexes also promote the nucleophilic addition of water to pyridine-2-carbonitrile and mononuclear complexes containing pyridine-2-carboxamidate ligands are formed (12a,b). The new compounds have been characterized by partial elemental analyses, conductance measurements and spectroscopic (IR, 1H and 13C NMR) methods. The crystal structures of compounds 6b and 11a have been determined by X-ray diffraction analysis.